On interface and twin boundaries in a forged Ti-47Al/TiB sub 2 alloy

Journal Article · Fri May 15 00:00:00 EDT 1992 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(92)90271-F· OSTI ID:7000372

Popoola, O; Cordier, C; Pirouz, P; Heuer, A H ^[1]

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1. Dept. of Materials Science and Engineering, Case Western Reserve Univ., Cleveland, OH (US)

This paper discusses XD (exothermic dispersion) processed TiAl/TiB{sub 2} alloys which are a new class of intermetallic composites with improved toughness, creep resistance and oxidation resistance at high temperatures. They generally have a two-phase {alpha}{sub 2} + {gamma} matrix (Ti{sub 3}Al (DO{sub 19}) and TiAl (L1{sub 0} structures, respectively), which contains monocrystalline TiB{sub 2} particles. Although the deformation mechanisms of these alloys are essentially the same as those of conventional TiAl alloys, dislocation substructures, particularly dislocations at {alpha}{sub 2}/{gamma} interfaces, remain to be unambiguously identified. In a recent paper on a Ti-45Al/TiB{sub 2} alloy, these interfacial dislocations were assumed to be misfit dislocations with 1/6 {l angle}112{r angle}{sub {gamma}}. Burgers vectors and their presence was attributed to boron interstitials in the {gamma} matrix, However, the {alpha}{sub 2} phase has been shown to getter interstitial impurities from the {gamma} phase, thus increasing the ductility of the two phase alloy. Moreover, 1/6 {l angle}112{r angle}{sub {gamma}} partial dislocations generally result from the dissociation of glissile {gamma} dislocations during deformation and cannot be resolved by conventional weak beam electron microscopy because of their small separation distances. Their assumed presence is also unusual, in that lattice mismatch is not normally accommodated by partial dislocations.

• OSTI ID: 7000372
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 26:10; ISSN SCRME
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
BORIDES
BORON COMPOUNDS
BURGERS VECTOR
CHEMICAL REACTIONS
COMPOSITE MATERIALS
CREEP
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
FABRICATION
FORGING
HARDNESS
INTERFACES
INTERMETALLIC COMPOUNDS
INTERSTITIALS
LINE DEFECTS
MATERIALS
MATERIALS WORKING
MECHANICAL PROPERTIES
MICROSTRUCTURE
OXIDATION
POINT DEFECTS
TEMPERATURE DEPENDENCE
TITANIUM ALLOYS
TITANIUM BORIDES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TWINNING